x,y=input('输入只因、兔总只数x及总腿数y并用空格隔开:').split(' ')
x=int(x)
y=int(y)
a=2*x-0.5*y
b=0.5*y-x
if a>0 and b>0 and a==int(a) and b==int(b):
    print('只因有{}只，兔有{}只'.format(a,b))
else:
    print('false')